Which leads to a really important question. Are the kids who are vaping kids who would otherwise be smoking, or is vaping capturing children that would never have touched a tobacco product otherwise? Until now, the answer depended on which side of the vaping debate you were on. Supporters would argue that vaping is probably safer than smoking – so if vaping is keeping a kid from using cigarettes that's just great. Opponents would say that vaping is capturing kids who would never smoke, and may act as a gateway to future cigarette use, erasing the gains we've seen lo these past 30 years.

Researchers used data from the Children's Health Study, including around 5500 11th and 12th graders from southern California schools from 1995 to 2014. The study asked the kids about a variety of tobacco-related behaviors, and, after 2004 (when e-cigarettes were introduced) began asking questions about vaping.

The current use data appears here:

current use of tobacco products

What you can see is a steady decline in cigarette use, mirroring the national trend from 1994 to 2004 when just 9% of kids reported smoking in the past month. In 2014, that rate was even lower – 7.8%. But if you include vaping, the rate is 14%. And roughly half of that group ONLY used e-cigarettes.

OK so what does this mean? If we are to believe that vaping replaces smoking, we'd like to see similar nicotine-use rates in 2014 as in 2004 – or less really, considering that usage has been declining pretty nicely since 1995. But we don't. The implication, according to the authors, is that vape-culture has spread to kids that would NOT have otherwise smoked. As vaping is not benign (nicotine has adverse effects on the developing brain, some of the chemicals might damage the lungs) these kids are being exposed to a risk they would not otherwise be exposed to.

Which is not to say that the other side of the argument isn't valid. Some kids may be vaping where, in a vape-free world, they would be smoking, and that may be the lesser of two evils. But on the whole, the theory that vaping is moving kids away from cigarettes without bringing new kids into the fold may be dissipating.